Display boards are known where the outlines of the characters to be displayed are delineated by a series of individual light sources. Depending on the size and scale of the display board, these light sources may be light emitting diodes or individual filament bulbs. The light sources are switched on in predetermined patterns, depending on the character which is to be displayed.
The appearance of these types of display is often not very satisfactory, mainly because they rely on the viewer being able to interpret a pattern of individual light sources as a particular character being displayed.